Sound recorder and reproducer



March 12, 1940. M. BENDER SOUND RECORDER AND REPRODUCER Filed May 11, 1936 2 Sheets-Sheet l INVENTOR Bwmer M ATTORNEY March 12, 1940. M. BENDER scum: RECORDER AND REPRODUCER 2 sneets sneet 2 Filed May 11, 1936 may/1. m

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Patented Mar. 12, 1940 PATENT orri cr I v 2,193,443 I SOUND RECORDER AND REPRonUcER Max Bender, Los Angeles, Calif., assignor to United Acoustigraph Corporation, a corporation of Nevada Application May 11, 1936, Serial No. 79,019 Y 2 Claims. (01. 179-10041) This inventionrelates to recording sound in a relatively hard material such as Celluloid or motion picture film.

One suggested method of forming such a rec- 0rd is by drawing the film against the cutting edge of a recording stylus while vibrating the stylus in accordance with the sound to be recorded. With hard material such as film, there is a tendency of the needle to dig itself into the film and the principal object of the presentinvention is to provide an improved means for preventing this and at the same time controlling the depth of groove cut.

Other objects of my invention will appear from the following description taken in connection with the accompanying drawings wherein Figure 1 is a side elevation of a combined sound recorder and reproducer showing one form of my invention} Figure 2 is a top plan view of the structure shown in Figure 1 with a portion shown in section taken on the line 2-2 of Figure 1;

Figure 3 is a front elevation of a modified form of spacer bar showing the relative position of the bar and cutting stylus;

Figure 4 is similar to Figure 3 but showing a modification;

Figure 5 is a front elevation partly broken away of a modified form of recorder and reproducer;

Figure 6 is a central vertical sectional view taken on the line 66 of Figure 5;

Figure 7 is a horizontal sectional View taken on the line 1-! ofFigure 5;

Figure 8 is a top plan view of one of the adjustable pole pieces of the recorder shown in Figure 5;

Figure 9 is a detail side elevation of the armature with the means for attaching the recording and reproducing styluses;

Figure 10 is a bottom plan view of the structure shown in Figure 9;

Figure 11 is a front elevation of the slightly modified form of spacing and control bar; and

Figure 12 is a side elevation of the structure shown in Figure 11.

Referring more particularly to Figure 1, It] represents a strip of tough material such as plasticized cellulose adapted to be drawn over an anvil or roller H. The film may be formed as an endless band and the record may be helical in form thus covering a large part or the entire surface of the film. A convenient way of making such an endless band is to coat a cylinder with surface of hardened steel may then be passed around the-coatingunder sufiicient pressure and if desired at a somewhat elevated temperature in order to deform or stretch the Celluloid slightly sothat its inner diameter is slightly greater than the outer diameter of the cylinder. The belt of Celluloid may thenbe readily removed from the cylinder.

Reference character I5 denotesa combined recorder and reproducer comprising a casing l6 enclosing electromagnets (not shown) which cooperate with anarmature ll' to record or reproduce sound in a manner well understood. Thearmature l 1 is formed at one end as a sleeve 18 adapted to receive a reproducing stylus 2!! firmly 5 held in position by a screw 2 I.v

The opposite end of the'armature H is formed as a sleeve Z2 adapted to 'receive a recording stylus 25 secured in position by the screw 25. The stylus 24 is provided with a cutting edge directed against the motion of the film as is indicated by the arrow. In the recorder disclosed, the record groove cut is of the-'so-called lateral type, but the device may also be used to cut a groove of th hill and dale type.

Pivotally mounted between brackets 27 secured to the'casing I5 is a spacer member or bar 30 formed with an enlarged foot which is adapted to bear against the surface of the film l0 and adapted to span a number of adjacent sound grooves. The lower surface of the foot 3! is curvedeccentric to the pivotal axis so movement of the foot toward the cutting stylus lowers the casing and permits the cutting of a deeper groove in the film, while movement of the foot away from the stylus raises the casing, thus decreasing the depth of the groove. It will of course be understood that the recorder and reproducer will be supported to rest on the film by gravity or in any othermanner as is usual in the art. I

For the purpose of adjusting the spacing member 30 and holding it in adjusted position, I provide a screwthreaded lug 3 3 secured in the wall of the casing IS with an adjusting nut 35 and a looking nut 36, the upper end of member 3i) being bifurcated and embracing the lug 34.

It will be noted that the foot 3! contacts with the film at a point adjacent to and 'in front of the cutting edge of the stylus 25. In this po-: sition it not only prevents excessive digging into the film by the cutting edge of the recording stylus but also holds the material of the film which lies in front of the edge between the upper cutting face of the'stylus and the bottom of the foot 3|. This prevents disturbing vibrations and insures smooth and even cutting.

Suitable means not shown is provided for shifting the recorder so that the reproducing stylus may be made to engage the groove when it is desired to reproduce the sound recorded.

In certain cases I may position the foot of the spacing and control bar alongside of the recording stylus 2 3 and in such case I form the bar 36A as shown in Figure 3 with an offset foot 3 IA. The

offset portion serves to throw off the shaving.

which is out from the thermoplastic by the stylus. As an alternative construction, I may use the form of bar iown at 39' in Figure 4 having a bifurcated foot 3! which embraces the stylus.

Referring more particularly to the embodiment of the invention shown in Figures 5 to 10 inclusive, the combined recorder and reproducer includes a frame of brass or similar non-magnetic material. Frame 59 comprises a side plate 5! formed with a central enlargement 52 and a lower flange portion 53 forming a base for the recorder. Suitably mounted on the frame 50 is a permanent magnet 55, the lower ends or poles of which are adapted to rest in contact with pole pieces 58 adjustably mounted. on the base plate 53, the pole 58 being secured in position by means of screws 59 which extend through slots 6E] in the base plate and thence into the pole pieces.

Also mounted on the base plate 53 is a coil M which serves to carry the recording or reproducing current. As will be seen from Figures '7 and 8, the pole piece 58 is formed with a half pyramidal extension at one end forming a pole tip and is cut away as indicated at 66 so that in the adjusted position of the pole piece as shown, for example, in Figure 7, the pole piece substantially embraces the coil 64.

Mounted in a sleeve extension 10 of the base plate 53 is a pin bearing H, shown at the right of Figure 6, and in alignment therewith and extending through the enlargement 52 of the frame 59 is an adjustable screwthreaded bearing 12 adapted to be held in adjusted position by a looking nut M. Mounted to rotate in the bearings H and I2 is a pin 15 which extends through and is rigidly secured in the armature structure 16. This armature is formed of aluminum alloy preferably heat treated, and as may be seen from Figures 9 and 10 has one end inclined and split at T3 forming a tubular holding portion 18 for receiving the reproducing stylus which is clamped therein by a screw 89. Adjacent its opposite end the armature structure 15 is formed with a downward inclined portion 8| having an opening 32 therein for receiving the recording stylus 83 which is suitably secured in position by a screw 84.

The armature structure or frame 16 is cut away to form an opening 86 in which is received a plate or armature 81 preferably of soft Norway iron. This plate as will be seen from Figure 6 extends from within the coil 64 outward between the tips of the pole pieces 58.

For the purpose of damping the vibrations of the armature 16, I provide two damping pads 90 held in a cylindrical opening or boring 9| in the plate 5| of the frame 50. Portions 92 of this boring are serewthreaded for receiving an adjusting screw 93 and between the inner end of the screw 93 and the pad 90 is a cylindrical follower 94, preferably formed of brass. The pads 90 may be formed of rubber, felt or any elastic material.

The control and spacing barv or lever 95 in the form of invention shown in Figure 6 is provided with a foot 9'! and this bar is pivoted at 98 in brackets 99 secured to the frame plate 5| by screws I90. The upper end of the bar 96 is bifurcated at NH and embraces a screwthreaded rod I92 secured as shown in the enlargement 52 of the recorder frame. Surrounding the rod I92 is a helical spring I04 bearing at one end against the rear wall of an opening I95 in the enlargement 52 and at the other end against the bar 96. For adjusting the control bar 96, I provide a nut H15 screwthreaded on the bar I92 and a lock nut Hi5 adapted to bear against the nut I05.

The control bar I I 9 shown in Figures 11 and 12 is provided with a foot III, the front ID! of which is cut on a radius eccentric to the pivoting point, to get the movement to raise and lower the head and providing a surface contact with the film. This is also true, it will be noted of the bar 96 shown in Figure 6. The radius of the are at the foot of the lever is substantially greater than the radius of the anvil over which the film moves.

Having now described my invention, what I claim and desire to secure by Letters Patent is:

1. An electromagnetic recording device for cutting a sound record in a moving film of plasticized cellulose, said device comprising a casing, a stylus having a cutting edge positioned against the motion of the film, a spaced member pivotally magnet, an armature structure comprising a supporting frame of light non-magnetic material supported in said frame and being partly in said coil and partly between the poles of the magnet and styluses supported at opposite ends of the frame.

MAX BENDER. 

